The embodiments described herein relate to the field of medical imaging equipment, especially to a magnetic resonance (MR) system, and particularly to a mechanical structure for driving and supporting cradle.
As shown in FIG. 1, a MR system usually includes a table (1), a magnet (2) and a rear pedestal (3). The table (1) is movable in forward and reverse and can move up and down. A cradle (4) on the table can move relative to the table so as to carry a patient into the magnet bore. When a front part of the cradle passes through the magnet bore and moves out of the magnet bore, a bridge (5) supports the front part of the cradle. The rear pedestal includes a cradle supporting element (6) and a drive motor (7). The drive motor drives the cradle supporting element to provide support to the protruding cradle when the cradle passes though and protrudes from the magnet bore.
Such known structure has the following problems. Because the table must be movable and can move up and down, the whole cradle (front part and rear part) tightly fits within the magnet bore, and thus it is difficult to realize a longer scanning range. Besides, in an emergency (e.g. when the system is out of power), the cradle inserted into the magnet bore cannot be withdraw immediately. Instead, the cradle can only be pulled out of the magnet bore by an operator manually. Moreover, the rear pedestal requires a rather large room, and thus the MR system is required to be housed in a large scanning room. As such, a facility to perform operations, such as surgical procedure, while performing MR scanning may be difficult to obtain.
The rear pedestal mainly has two functions. First, the rear pedestal forms a support for the cradle moving into the magnet bore so as to reduce cradle sag. The read pedestal further drives the movement of the cradle. Therefore, a new structural for driving and supporting cradle is described below to remove the rear pedestal. The embodiments described herein are further configured to realize a longer scanning range and to ensure timely release of the cradle in case of emergencies.
U.S. Pat. No. 7,430,772 discloses a single-cradle driving and supporting mechanism realized with three toothed racks. However, the single-cradle limits the scanning range, the cost of the structure of three toothed racks is high, and the control precision thereof is low. Further, U.S. Pub. No. 2007/0143921 discloses a double-cradle driving and supporting structure realized with a double belt pulley. However, the table cannot move freely to ensure safety since the drive motor is located on the table base.